Friction sound in knee movement is considered to be chondromalacia patella, osteoarthritis or meniscus injury. Chondromalacia patella is caused by degeneration of the patella, which is mainly manifested by unevenness of the joint surface, and friction sound will appear when flexing and extending the joint, and some patients will also have knee pain and weakness. Osteoarthritis, mostly occurs in the elderly, after people get older, bone and joint degeneration and proliferation caused by the narrowing of the joint space, cartilage wear, osteophytes, when the knee joint activities have friction sound. Meniscus injury, because the knee trauma caused by the meniscus tear, when the activities of the knee joint ruptured meniscus and articular cartilage friction sound, some will also have the phenomenon of jamming. Therefore, if you have friction sound when you move your knee, you should go to the hospital in time, and standardize the treatment under the doctor’s guidance.